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Title

Author

Defense Date

Document Type

Thesis - NSU Access Only

Degree Name

M.S. Marine Biology

Department

Oceanographic Center

First Advisor

Richard E. Dodge

Second Advisor

Curtis Burney

Third Advisor

Peter K. Swart

Fourth Advisor

Lou Fisher

Abstract

The objectives of the study were to attempt to differentiate among potential sources of nutrients contributing to past algae blooms occurring off the coast of northern Broward and Palm Beach Counties in Florida. To accomplish this, hermatypic reef-building corals were collected from different depths and latitudes over an area extending from the southern part of Broward County to the southern portion of Palm Beach County. The CaC03 skeletons of these corals were X-rayed and then sampled using their internal annual density growth increments as chronological guides. The trace element barium and the isotopes of carbon and oxygen isotopes were measured allowing chemical time series to be developed. Measurements of the trace metal barium in coral skeletons were performed to assess the contribution of cold, organic-rich waters to the past summertime algal blooms (higher skeletal concentrations than in control sites during that time). Skeletal isotopic measurements of these corals were also conducted to possibly record oxygen enrichment (deeper cold waters) and carbon (deeper, organic and nutrient-rich waters) depletion.

Results demonstrate historical Ba levels in corals and variability among species, seasons, years, and sites. The study did not reveal a straightforward relationship between algal bloom events and the measured chemical parameters through increases or decreases that coincided with known recent algae blooms. Possible sources of the nutrients and the logic of how nutrient sources might be differentiated by our measurements are discussed. If the source of nutrients is coastal runoff or point source, then shallow corals nearest the inlets should record the highest barium levels (because this element is also concentrated in riverine effluents), particularly during the wet season (summertime).